Minimally-invasive devices and methods for treatment of congestive heart failure

ABSTRACT

A method of treatment of congestive heart failure comprises the steps of introducing an aortic occlusion catheter through a patient&#39;s peripheral artery, the aortic occlusion catheter having an occluding member movable from a collapsed position to an expanded position; positioning the occluding member in the patient&#39;s ascending aorta; moving the occluding member from the collapsed shape to the expanded shape after the positioning step; introducing cardioplegic fluid into the patient&#39;s coronary blood vessels to arrest the patient&#39;s heart; maintaining circulation of oxygenated blood through the patient&#39;s arterial system; and reshaping an outer wall of the patient&#39;s heart while the heart is arrested so as to reduce the transverse dimension of the left ventricle. The ascending aorta may be occluded and cardioplegic fluid delivered by means of an occlusion balloon attached to the distal end of an elongated catheter positioned transluminally in the aorta from a femoral, subclavian, or other appropriate peripheral artery.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of application Ser. No.09/950,917 filed on Sep. 12, 2001 now abandoned, which is a continuationof U.S. patent application Ser. No. 08/685,262 filed Jul. 23, 1996, nowU.S. Pat. No. 6,125,852, which is a Continuation-in-Part of applicationSer. No. 08/485,600, filed Jun. 7, 1995 now abandoned, which is aContinuation-In-Part of application Ser. No. 08/281,962, filed Jul. 28,1994 now abandoned, which is a Continuation-In-Part of application Ser.No. 08/163,241, filed Dec. 6, 1993, now U.S. Pat. No. 5,571,215, whichis a Continuation-In-Part of application Ser. No. 08/023,778, filed Feb.22, 1993, now issued as U.S. Pat. No. 5,452,733, the complete disclosureof which are hereby incorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

In congestive heart failure or CHF, the heart has become so enlarged asa result of viral infection, myocardial infarction or other disease thatit is unable to pump at a sufficient rate to maintain adequatecirculation of blood throughout the body. As a result, blood backs upinto the lungs, causing shortness of breath and other symptoms, and, ifleft untreated, the disease can lead to death.

For some patients, the CHF may be treated effectively with medication.However, in many cases, the disease progresses to a point at which thepatient requires a heart transplant. Unfortunately, due to a donorshortage, of the 40,000 patients who may require a transplant each year,only 2500 actually get one, with up to 15–20% of patients dying while onthe waiting list for a donor heart.

In response to the need for alternatives to transplant for treating CHF,a surgical procedure has been tried in recent years known as the“Batista Operation” after its developer, Dr. Randas J. V. Batista. Inthis procedure, a large section of the left ventricular wall is excisedfrom the heart and the wall then sewn back together, thereby reducingthe transverse dimension and volume of the left ventricle, the primarypumping chamber of the heart. The reduced volume of the ventriclepermits less blood to be present in the chamber during each of itscontractions, thus reducing the forces acting against the heart muscleas it contracts and allowing the heart to pump more effectively.

Although the Batista Operation can extend the life of a patient whowould otherwise die without a transplant, it is a highly invasive andtraumatic procedure. In order to expose the heart, the chest must beopened widely by sawing the sternum in half and spreading apart the ribcage, known as a median sternotomy, producing a great deal of pain, riskof infection, and long recovery time. For elderly or extremely illpatients, the trauma produced by the operation could contributesignificantly to the mortality and morbidity associated with theprocedure.

Moreover, the Batista Operation has typically been performed while theheart is beating, causing a great deal of blood loss through theventricular incision, and risking the introduction of air into thebloodstream, potentially causing stroke or other neurological problems.To reduce blood loss and the risk of air embolism, the heart could bestopped and isolated from the rest of the circulatory system during theprocedure by placing an external aortic cross-clamp on the ascendingaorta and using conventional cardioplegia and cardiopulmonary bypass.However, because such cross-clamps crush the walls of the aorta togetherin order to occlude the vessel, cross-clamps may produce the added riskof releasing calcific particles from the inner walls of the aorta, whichmay embolize in the bloodstream and produce neurological events such asstroke. Moreover, the risk remains that air will become trapped in theventricle after it has been closed, allowing the air to migrate to thebrain as soon as the cross-clamp is removed. Conventional cross-clampsalso require a large opening in the chest in order to gain access to theaorta, hindering any effort to reduce the trauma associated with theprocedure.

What are needed, therefore, are devices and techniques for the surgicaltreatment of CHF which are less invasive and less risky than the BatistaOperation, but which produce the benefits associated with reducing thevolume of the left ventricle. The devices and techniques shouldfacilitate the identification of an appropriate section of the leftventricular wall, excision or other reshaping of the section, and, ifthe section is removed, closure of the left ventricle, without requiringa gross thoracotomy or median sternotomy. If the left ventricle isopened, the devices and techniques should allow the patient to be placedon cardiopulmonary bypass and the heart to be arrested and isolated fromthe circulatory system without the need for an external aorticcross-clamp. Further, the devices and techniques should minimize thatrisk that either air and other emboli will be produced by the procedure.

SUMMARY OF THE INVENTION

The invention provides devices and methods for treating CHF, as well asother diseases resulting in an enlarged heart, that not onlysignificantly reduce the pain and trauma to the patient, but that mayreduce the risk of infection and the risk of neurological eventsassociated with the Batista Operation. The invention facilitates thereduction of left ventricular volume by removing a section of the heartwall or otherwise reshaping the ventricle without requiring a mediansternotomy or gross thoracotomy. The invention further allows theprocedure to be performed on cardiopulmonary bypass with the heartisolated and arrested, yet without the gross thoracic incision requiredby, or the risk of embolism produced by, conventional aorticcross-clamps. Moreover, the invention may significantly reduce the riskthat air will be introduced into the bloodstream and embolized to thebrain during or after the procedure.

In a first embodiment, the invention provides a method of reshaping apatient's heart, comprising the steps of:

introducing an aortic occlusion catheter through a patient's peripheralartery, the aortic occlusion catheter having an occluding member movablefrom a collapsed position to an expanded position;

positioning the occluding member in the patient's ascending aorta;

moving the occluding member from the collapsed shape to the expandedshape after the positioning step;

introducing cardioplegic fluid into the patient's coronary blood vesselsto arrest the patient's heart;

maintaining circulation of oxygenated blood through the patient'sarterial system; and

reshaping an outer wall of the patient's heart while the heart isarrested so as to reduce the transverse dimension of the left ventricle.

The ascending aorta is preferably occluded by means of an occlusionballoon attached to the distal end of an elongated catheter positionedtransluminally in the aorta from a femoral, subclavian, or otherappropriate peripheral artery. Cardioplegic fluid may then be deliveredupstream of the occlusion balloon through a lumen in that catheter,and/or delivered in a retrograde manner through a separate catheterplaced transluminally into the coronary sinus from a peripheral vein.While the heart is arrested, circulation of oxygenated blood ismaintained preferably by peripheral extraporeal cardiopulmonary bypass(CPB), wherein blood is removed from a peripheral vein via a venousdrainage catheter, filtered, oxygenated, and returned to a peripheralartery through an arterial return catheter.

By obviating the need for an aortic cross-clamp, the need for the mediansternotomy through which such a cross-clamp is placed is alsoeliminated. The left ventricle may then be reshaped and volumetricallyreduced using thoracoscopic instruments positioned through smallincisions, punctures or ports located in the intercostal spaces betweenthe ribs.

The invention further provides a method of reshaping a patient's heartcomprising the steps of:

introducing a tissue attaching device into the patient's chest;

engaging a first location on a wall of the left ventricle with thetissue attaching device; and

manipulating the tissue attaching device to attach the first location toa second location on a wall of the heart so as to reduce the transversedimension of the left ventricle, the user's hands remaining outside thepatient's chest when manipulating the tissue attaching device.

In some embodiments, a section of the left ventricular wall is excisedwith a cutting device, then the left ventricle is closed using sutures,staples or other means for wound approximation and closure, each appliedusing thoracoscopic instruments with the user's hands maintainedgenerally outside of the chest. In other embodiments, a section of theleft ventricular wall is gathered together or pursed outwardly orinwardly to produce one or more folds or pleats in the wall. These foldsor pleats are then thoracoscopically sutured, stapled or otherwisefastened permanently in place to reduce the transverse dimension of theleft ventricle.

In the method of the invention, the left ventricular wall may beapproached in several different ways. In one approach, one or more smallincisions, punctures, trocar sleeves, tissue retractors or other type ofports are placed in intercostal spaces in the left anterior and/orlateral side of the chest, preferably between the third and seventhintercostal spaces. This permits direct access to the outer wall of theleft ventricle on the lateral and posterior sides of the heart, usuallywith minor retraction of the apex of the heart anteriorly usingthoracoscopic graspers or other retraction instruments. The heart maythen be viewed directly through an intercostal port, or by means of athoracoscope positioned through an intercostal port to permit eitherdirect or video-based viewing of the heart.

In a second approach, ports are placed are in the right lateral side ofthe chest between the third and seventh intercostal spaces. Approachingthe heart from the right, an incision is then made in the left atrium onthe posterior side of the heart, and the incision retracted to exposethe mitral valve. The mitral valve apparatus is excised from the heart,providing access into the interior of the left ventricle through themitral valve annulus. A thoracoscopic scissors or knife is then used toexcise a portion of the left ventricular wall from the inside of thechamber, either under direct vision from a port in the right side of thechest, or under video-based vision using a thoracoscope positionedthrough a port into the heart. The procedure may be viewed from outsideof the heart as well by placing a thoracoscope through a port in theleft lateral or anterior side of the chest. The left ventricular wallmay then be closed using sutures, staples, or other means applied withan instrument introduced through the mitral annulus from the rightchest, or through a port placed in the left lateral or anterior side ofthe chest as described above.

In still other embodiments, a restrictive girdle or band is placedaround the outside of the heart to restrict the left ventricle to thedesired diameter or volume. The band or girdle is preferably elastic soas to expand and contract with the heart as it pumps. Preferably, thegirdle or band is applied to the heart using specialized thoracoscopicinstruments placed through intercostal spaces in the rib cage whilegenerally maintaining the user's hands outside the chest, therebyeliminating the need for a gross thoracotomy.

Because the chest is not grossly opened, the heart is isolated from therest of the circulatory system, and in some embodiments, even theventricle itself is not opened, the methods of the invention may reducethe risk that air will pass through the ventricular incision and intothe bloodstream. To reduce this risk even further, the invention alsoallows the chest to be flooded with carbon dioxide or other suitable gasduring the procedure to maintain the chest cavity free of air. A tubemay be placed through one of the intercostal ports and gas deliveredthrough the tube into the chest at a pressure suitable to ensure thatair cannot enter the chest cavity. Additionally, trocar sleeves ortubular ports may be used which have internal seals like those used forgaseous insufflation in laparoscopic procedures, thereby preventing theunwanted introduction of air into the chest. Further, where some risk ofair embolism is present due to the opening of the left ventricle,following closure the left ventricle and aorta may be flushed withsaline and then vented through a lumen in the aortic occlusion catheterwhile maintaining aortic occlusion, thereby removing any trapped airthat may be present.

The nature and advantages of the invention will become more apparent inthe following detailed description, taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an anterior view of a patient's torso schematicallyillustrating the use of an endovascular cardiopulmonary bypass systemaccording to the invention.

FIG. 2 is an anterior view of a patient's chest illustrating theplacement of intercostal ports and thoracoscopic instruments accordingto the invention.

FIGS. 3–5 are posterior views of a patient's heart illustrating theremoval of a section of the left ventricle and closure of the leftventricular wall according to the invention.

FIG. 6A is a transverse cross-section of a patient's chest illustratingan alternative approach to the left ventricle according to theinvention.

FIG. 6B is a transverse cross-section of a patient's chest illustratingan alternative method of ventricular volume reduction according to theinvention.

FIGS. 6C–6D are close-up cross-sections of the ventricular wallillustrating additional steps in the method of FIG. 6B.

FIGS. 7A–7B are transverse cross-sections of a patient's heart beforeand after treatment, respectively, illustrating the bifurcation of theleft ventricle according to the invention.

FIG. 7C is a posterior view of a patient's heart illustrating theexterior shape of the left ventricle after bifurcation as in FIG. 7B.

FIG. 8A is a side view of a tissue gathering device according to theinvention.

FIG. 8B is a top view of the distal end of the tissue gathering deviceof FIG. 8A.

FIG. 9A is a cross-section of a portion of the left ventricleillustrating the use of the tissue gathering device of FIG. 8A accordingto the method of the invention.

FIG. 9B is a posterior view of a patient's heart illustrating the heartafter treatment using the tissue gathering device of FIG. 8A.

FIG. 10 is a posterior view of a patient's heart illustrating the use ofa heart measurement device according to the invention.

FIG. 11 is a transverse cross-section of a patient's thorax illustratingthe use of a left ventricular measurement device according to theinvention.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

Referring to FIG. 1, an endovascular cardiopulmonary bypass (CPB) systemuseful in the method of the invention is illustrated as it is used in apatient. Additional aspects of such endovascular CPB systems suitablefor use in the methods of the invention are described in the followingpatent applications, which are incorporated herein by reference: Ser.No. 08/282,192, filed Jul. 28, 1994, now U.S. Pat. No. 5,584,803, Ser.No. 08/612,341, filed Mar. 7, 1996, and Ser. No. 08/486,216, filed Jun.7, 1995, now U.S. Pat. No. 5,766,151. The system includes a venousdrainage cannula 20 placed into a femoral vein FV (or other suitableperipheral vein) and preferably having sufficient length to extend intothe inferior vena cava IVC, the right atrium RA or the superior venacava SVC. Venous drainage cannula 20 is connected to an extracorporealCPB system 22, which filters and oxygenates the blood withdrawn from thepatient. The system further includes an arterial return cannula 24placed into a femoral artery FA (or other peripheral artery such as thesubclavian) through which CPB system 22 pumps oxygenated blood into thearterial system. Arterial return cannula 24, venous drainage cannula 20and CPB system 22 are configured to provide full cardiopulmonary bypasswith the patient's heart arrested.

The endovascular CPB system further includes an aortic occlusioncatheter 26 that is positioned into femoral artery FA through a port 28at the proximal end of arterial return cannula 24. Port 28 has ahemostatic seal (not shown) to prevent blood loss when occlusioncatheter 26 is positioned through the port. Occlusion catheter 26 has anocclusion balloon 30 at its distal end and a length sufficient to allowocclusion balloon 30 to be positioned in the ascending aorta AA, usuallyat least about 80 cm. Occlusion catheter 26 preferably has at leastthree lumens, including an inflation lumen in communication with theinterior of balloon 30 for delivery of an inflation fluid from a syringe32 or other inflation device. A pressure lumen is also provided whichcommunicates with a pressure port in the catheter distal to balloon 30,allowing pressure to be monitored by means of a pressure measuringdevice 34. Occlusion catheter 26 further includes a main lumen incommunication with an additional port distal to balloon 30 to allowdelivery of cardioplegic fluid from a cardioplegic fluid source 36 andto facilitate venting the aortic root by means of a suction pump 38. Atwo-way valve 40 permits selecting between cardioplegic fluid deliveryor aortic root venting via the main lumen.

An optional component of the endovascular CPB system is a coronary sinuscatheter 42 positioned transluminally into the coronary sinus CS via theinternal jugular vein JV in the neck, the superior vena cava SVC, andright atrium RA. Coronary sinus catheter 42 permits retrograde deliveryof cardioplegic fluid in conjunction with or instead of antegradedelivery through aortic occlusion catheter 26. The distal end ofcatheter 42 includes a balloon 44 configured to occlude the coronarysinus CS. Sinus catheter 42 has at least two lumens, including aninflation lumen in communication with balloon 44, and a delivery lumenin communication with a port distal to balloon 44 for deliveringcardioplegic fluid into coronary sinus CS. A third lumen may optionallybe provided for pressure measurement through a port distal to balloon44.

As an additional option, an endovascular venting catheter may beintroduced into a vein in the neck and advanced through the superiorvena cava, the right atrium, the right ventricle and into the pulmonaryartery for venting blood from the heart, as described in co-pendingapplication Ser. No. 08/415,238, filed Mar. 30, 1995, which isincorporated herein by reference.

In use, with venous drainage cannula 20 and arterial return cannula 24in place and blood circulating through extracorporeal CPB system 22,aortic occlusion catheter 26 is inserted through arterial return cannula24 and slidably advanced toward the heart until occlusion balloon 30 isin the ascending aorta AA. Balloon 30 is then inflated to fully occludethe aortic lumen between the coronary ostia (not shown) and thebrachiocephalic artery BA. Cardioplegic fluid, usually consisting of acold potassium chloride solution mixed with oxygenated blood, is thendelivered into the ascending aorta through the main lumen of occlusioncatheter 26, from which it flows into coronary arteries and perfuses themyocardium, stopping cardiac contractions. If coronary sinus catheter 42is utilized, balloon 44 may be inflated and cardioplegic fluid deliveredinto the coronary sinus CS, from which it flows through the coronaryveins to perfuse the myocardium. Between periodic infusions ofcardioplegic fluid, valve 40 is switched to allow the aortic root to bevented of fluid via occlusion catheter 26. Aortic root pressure may becontinuously monitored using pressure measurement device 34.

Prior to arresting the heart, it may be desirable to perform a number ofsurgical steps in the operation up to the point of actually cutting intothe myocardium so as to minimize the time for which the heart isstopped. A number of surgical ports 50, usually between about one andsix, are placed in intercostal spaces IS between the ribs R. These portsmay be simple plastic tubes having flanges at their proximal ends toprevent passage entirely into the chest and having sufficient rigidityto retract intercostal tissue so as to form an opening. Trocar sleevesor small bladed rib retractors may also be used. A soft tissue retractorthat may be particularly useful in the method of the invention isdescribed in application Ser. No. 08/610,619, filed Mar. 4, 1996, nowU.S. Pat. No. 5,810,721, which is incorporated herein by reference. Insome cases, instruments may be placed directly through incisions orpunctures between the ribs without any type of retraction. In any case,all of the aforementioned means of access into the chest will bereferred to herein as ports.

Ports 50 may be positioned in any of several regions of the chest,depending upon the desired approach to heart. For approaching the leftventricle on the posterior side of the heart, ports 50 are preferablyplaced in the fourth, fifth, sixth or seventh intercostal spaces on theleft anterior and/or left lateral side of the patient's chest. Forapproaching the left ventricle from within the heart via the left atriumand the mitral valve, ports 50 are placed in the right lateral side ofthe chest in the second, third, fourth, fifth, or sixth intercostalspaces. Of course, it will be understood that the exact location ofports 50 will depend upon the location of the surgical site on theheart, individual patient anatomy, and surgeon preference.

One or both of the patient's lungs may have to be partially or fullycollapsed during the procedure in order to gain access to the heart.With the lungs collapsed, the pericardium PC is incised, as illustratedin FIG. 2, using thoracoscopic scissors 52, an electrocautery probe orother appropriate cutting devices, along with graspers 54 or otherretraction devices, inserted through ports 50. Suitable instruments aredescribed in U.S. Pat. No. 5,501,698, which is incorporated herein byreference. A thoracoscope 56 is inserted through one of ports 50 tofacilitate visualization. Thoracoscope 56 includes a camera 58 whichproduces a video image of the interior of the chest that can be viewedon a video monitor (not shown). Various conventional thoracoscopes maybe used, including the articulating Welch-Allyn DistalView 360(Welch-Allyn, Skaneateles Falls, N.Y.), or a 30□ angled endoscopeavailable from Olympus Optical (Lake Success, N.Y.). The surgeon mayalso look directly into the chest through ports 50, assisted byillumination of the chest by means of a light probe inserted through aport. The pericardium is opened or removed from around the leftventricle to expose the surgical site,

In a first embodiment of the ventricular volume reduction procedure ofthe invention, a portion of an outer wall of the left ventricle isremoved and the wall then re-closed so as to reduce the traversedimension and volume of the ventricular chamber. Referring to FIG. 3, aposterior view of the heart, with the patient's heart arrested andcirculation maintained by CPB system 22, a cutting device such as aknife 60 along with thoracoscopic graspers 62 are inserted though ports50 and used to excise the desired portion of the ventricular wall.During the procedure some retraction of the heart may be required, byfor example, grasping the apex of the heart with graspers 62 and movingthe apex anteriorly so as to expose the posterior aspect of the leftventricle. Using knife 60, a stab wound is made near the apex AP of theheart and an incision extended superiorly toward the left atrium in anarc bowing outwardly toward the left side of the heart. A secondincision is made from the apex in an opposing arc bowing outwardlytoward the right side of the heart and intersecting the first incisionnear the coronary sinus CS, allowing a football-shaped section ofmyocardial tissue to be removed. This leaves an opening OP in the leftventricular wall as illustrated in FIG. 4.

Opening OP is then sutured closed using thoracoscopic needle drivers 64to drive curved needle 66 and suture 68 through ventricular wall VW andusing graspers 62 to assist in approximating the opposing edges of theopening. Usually a relatively coarse running stitch is placed in thewall to draw opening OP closed, and a finer running stitch is thenapplied to ensure the wound is hemostatically sealed.

The exact location and amount of tissue removed from the leftventricular wall will vary according to the type and severity of diseaseand other factors. The effectiveness of the heart in pumping blood willgenerally be increased by reducing the transverse dimension of the leftventricle so as to reduce the overall volume of the chamber. This allowsless blood to flow into the left ventricle before each contraction,thereby reducing the outward force of the blood against the ventriclewhen it contracts. Preferably, a sufficiently large section of theventricular wall will be removed to reduce the ventricle to having atransverse dimension (generally perpendicular to the interventricularseptum) on the order of 4 to 7 cm.

Generally, opening OP in the left ventricular wall will be formedbetween the anterior and posterior papillary muscles, avoidingunnecessary damage to the mitral valve apparatus. In some cases,however, the mitral valve apparatus is damaged or removed during theprocedure, requiring replacement or repair of the valve followingremoval of the ventricular wall section. This may be accomplished byintroducing an annuloplasty ring or prosthetic valve into the heartthrough ports 50 and opening OP and securing the prosthesis at themitral valve position using thoracoscopic instruments introduced throughports 50. Alternatively, the mitral valve may be replaced via ports inthe right lateral side of the chest by entering the left atrium, usingthe techniques described in co-pending application Ser. No. 08/465,383,filed Jun. 5, 1995, now U.S. Pat. No. 5,682,906, which is herebyincorporated herein by reference.

Following closure of the left ventricular wall, ports 50 are removed andthoracic incisions are closed. Cardioplegic fluid infusions arediscontinued and the aortic root is vented through occlusion catheter 26to remove any air or other particles which may be present in the heartor aorta. If desired, saline may be delivered through the main lumen ofthe occlusion catheter into the aortic root, or a small catheter may beadvanced through the occlusion catheter and into the left atrium throughthe aortic valve to deliver saline into the left ventricle. The heartmay be compressed using thoracoscopic probes to urge air out of the leftventricle. The saline is then vented through occlusion catheter 26 toremove air and other emboli. In order to restart heart contractions,occlusion balloon 30 on aortic occlusion catheter 26 is deflated toallow blood from arterial return cannula 24 to reach the coronary ostia.If cardiac contractions do not resume spontaneously, an electric shockmay be delivered to the heart using thoracoscopic or externaldefibrillation paddles. When the heart is in sinus rhythm, the patientis weaned from cardiopulmonary bypass, vascular punctures are closed,and the patient recovered from general anesthesia.

Because the left ventricle is opened during the procedure, it will bedesirable to keep air out of the chest cavity to the maximum extentuntil the ventricle is closed. For this purpose, ports 50 may beprovided with gaseous seals like those used in laparoscopic trocarsleeves to maintain an air-free environment within the chest. Inaddition, a gas such as carbon dioxide that is not likely to embolize inthe blood stream may be delivered into the chest at a sufficient rateand pressure to prevent air from entering. Other techniques forpreventing air embolism are described in co-pending application Ser. No.08/585,871, filed Jan. 12, 1996, now U.S. Pat. No. 5,849,005 which isincorporated herein by reference.

FIGS. 6A–6D are transverse cross-sections of a patient's thorax andheart illustrating additional embodiments of the method of theinvention. In these embodiments, a right chest approach is used similarto that described in co-pending application Ser. No. 08/465,383, nowU.S. Pat. No. 5,682,906, which has been incorporated herein byreference. That application describes techniques for opening thepericardium, forming and retracting an atrial incision, removing themitral valve, and implanting a valve prosthesis which may be utilized inthe method of the present invention.

Preferably, ports 50A are placed in the second, third, fourth, fifth, orsixth intercostal spaces in the right lateral side of the chest.Optionally, additional ports 50B may be placed in the left lateral orleft anterior sides of the chest to approach the left ventricle on theposterior side of the heart, as described above with reference to FIGS.1–2. An opening is first formed in the pericardium using thoracoscopicinstruments inserted through right chest ports 50A and/or left chestports 50B so as to expose the left atrium LA and the left ventricle LV.A thoracoscope 70 may be inserted through one of ports 50A to view theinterior of the chest, or the surgeon may view the chest cavity directlyby looking through ports 50A. If desired, one or more of ports 50A maybe configured to provide a wider opening into the chest to allow greatermaneuverability of instruments and to facilitate direct vision into thechest, such as the oval-shaped port described in application Ser. No.08/465,383, now U.S. Pat. No. 5,682,906, or the soft tissue retractordescribed in application Ser. No. 08/610,619, now U.S. Pat. No.5,810,721, referenced above. Preferably, these will not require cuttingor removing the ribs, and will minimize any retraction of the ribs,although in some cases it may be desirable to retract the ribs slightlyor remove a small portion of a rib to provide greater access into thechest. However, ports 50A will generally not be large enough to allowthe surgeon's hands to be placed into the chest, although it may bepossible to place one or more individual fingers into the chest.

The right lung is collapsed, the pericardium is opened and the patientis on CPB with the heart arrested as described above. An incision ismade in the left atrium on the right lateral/posterior aspect of theheart using thoracoscopic scissors or knife inserted through a port 50A.The atrial incision is then retracted anteriorly using a thoracoscopicretractor 72. Suitable retractors are described in co-pendingapplication Ser. No. 08/577,547, filed Dec. 22, 1995 which is herebyincorporated herein by reference. With the atrial incision retracted inthis manner, the mitral valve is exposed at a direct line of sight froma port 50A in the fourth, fifth, or sixth intercostal space in the rightchest. The mitral valve leaflets may then be removed using thoracoscopicscissors so that the left ventricle LV is visible through the mitralvalve annulus VA. The valve leaflets and chordae tendonae mayalternatively be left intact, and a thoracoscope introduced through thevalve into left ventricle LV to provide visualization within thechamber.

In the embodiment shown in FIG. 6A, a section of the left ventricularwall VW is then removed using elongated thoracoscopic scissors 74 orother suitable cutting device introduced through a port 50A and valveannulus VA. Scissors 74 are used to excise a football-shaped section ofventricular wall tissue, preferably between the anterior and posteriorpapillary muscles. An additional thoracoscope 76 may be introducedthrough left lateral chest ports 50B with the left lung collapsed tovisualize the outer wall of the left ventricle to ensure the desiredsection is removed without cutting into adjacent tissues.

The left ventricular wall is then closed in one of two ways. Ventricularwall VW may be sutured from within the chamber with thoracoscopic needledrivers introduced through right chest ports 50A and mitral valveannulus VA, or sutured from outside the heart using needle driversinserted through left chest ports 50B as described above in connectionwith FIG. 5. Advantageously, should the mitral valve require repair orreplacement after the ventricular wall has been closed, excellent accessis provided through right chest ports 50A to implant either areplacement valve or an annuloplasty ring, or perform any necessarysurgical repair of the valve, in the manner described in co-pendingapplication Ser. No. 08/465,383, now U.S. Pat. No. 5,682,906, alreadyincorporated herein by reference. The left atrium is then closed. Ports50A, 50B are removed and thoracic incisions are closed. The heart isrestarted and the patient is weaned from cardiopulmonary bypass asdescribed above.

In an alternative embodiment, shown in FIGS. 6B–6D, rather than cuttingentirely through the heart wall to remove a section of the wall, asection of the inner wall of the heart is removed while leaving a thinlayer of the outer wall intact. For this purpose, a thoracoscopictissue-removing instrument 61, such as an end-biting biopsy or rongeurtype instrument, may be utilized which has a pair of pivotable jaws 63with tissue-cutting cup-shaped tips 65 that interact in a shearingrelationship to bite off a portion of tissue, as shown in FIG. 6C. Avariety of other conventional endoscopic tissue removal instruments mayalso be used. In this way, a very thin section of the ventricular wallis created in the area which would otherwise be removed according to thealternative methods described above. Ventricular wall VW is then drawntogether and sutured so that the thin section of the wall is pursedoutward, as shown in FIG. 6D. A thoracoscopic needle driver 67 may beinserted through a right chest port 50A and through the mitral valve toapply a suture 69, or a needle driver may be inserted through a leftlateral or anterior port 50B to apply sutures from the exterior of theheart. In some cases, it may be desirable to progressively draw theheart wall closer and closer together, by first drawing together only aportion of the thin-walled section and suturing it in place, thendrawing together a wider portion, suturing it, and repeating the processuntil the entire thin-walled section has been folded together and theventricle is of the desired dimension.

FIGS. 7A–7C illustrate a further embodiment of the method of theinvention. In this embodiment, rather than removing a section of theleft ventricle, the ventricle is reshaped by attaching a centrallongitudinal section of the ventricular wall VW to the interventricularseptum IS. This is most readily accomplished by inserting athoracoscopic tissue attachment device through left chest ports 50B(FIG. 2), exerting inward pressure against the left ventricular wall VWuntil it abuts septum IS, and securing wall VW to septum IS. The tissueattachment device comprises, in an exemplary embodiment, an insertiondevice 71 for applying a T-shaped fastener like that described inreissued U.S. Pat. No. Re34,021, incorporated herein by reference.Insertion device 71 has a tubular shaft 73 with a sharpened distal end75 used to penetrate ventricular wall VW and interventricular septum IS.A suture 77 is attached to a central portion of a fastener 80 (not shownin FIG. 7A) which is removably positioned in tubular shaft 73 duringinsertion. A second suture 79 is also attached to an end of fastener 80for removal purposes, as described in the aforementioned reissue patent.Once distal end 75 has penetrated system IS, an obturator (not shown) ispositioned through tubular shaft 73 so as to deploy fastener 80 into theright ventricle RV. Insertion device 71 is then removed from the heart,leaving sutures 77,79 extending through the septum IS and ventricularwall VW. A retainer 81, slidably mounted on sutures 77,79, is thenadvanced against ventricular wall VW to urge the ventricular wallagainst septum IS, as shown in FIG. 7B. A series of fasteners 80 areapplied in this way along a generally vertical line extending from theapex of the heart toward the superior aspect of the heart so as tobifurcate the ventricle into two separate chambers communicating witheach other and with the aortic valve AV and mitral valve MV at thesuperior end of the chambers. Each of the smaller chambers thus createdhas a smaller transverse dimension and volume than the left ventricle,and the contraction of each chamber is therefore opposed by a smalleroutward force from blood present in the chamber than that to which thesingle larger ventricle is subject. It will be understood that a varietyof tissue attachment techniques may be used instead of the T-shapedfastener illustrated, including suturing by means of a large curvedneedle and thoracoscopic needle drivers, or skin or fascia typestaplers. A particular advantage of this technique is that it does notrequire the left ventricle to be opened and exposed to air, therebyeliminating the risk of air embolism resulting from the procedure.Additionally, the technique avoids any loss of blood from the ventricle,allowing it to be performed on the beating heart, without occluding theaorta, arresting the heart, or placing the patient on CPB.

A further embodiment of a method of ventricular volume reduction willnow be described in connection with FIGS. 8A–8B and 9A–9B. In thisembodiment, a thoracoscopic tissue gathering device is utilized, anexemplary embodiment of which is illustrated in FIGS. 8A–8B. Tissuegathering device 84 comprises an elongated tubular shaft 86 and an innerrod 88 extending slidably through shaft 86. A tissue engaging member 90is attached to the distal end of rod 88. Tissue engaging member 90comprises a pair of jaws 92 biased away from each other and connected attheir proximal ends to rod 88. The lateral surfaces 94 of jaws 92 areengaged by the inner wall of shaft 86 such that sliding the shaftdistally relative to rod 88 urges jaws 92 toward one another. Aplurality of sharp points or teeth 96 extend inwardly from a distalportion of jaws 92 and are configured to penetrate the ventricular wall,as described below. Jaws 92 may be as narrow as the diameter of shaft 86or even narrower, if desired, with only one or two opposing teeth 96,but are preferably somewhat wider as illustrated, e.g. 1–5 cm in width(transverse to shaft 86), with three or more teeth 96 on each jaw, tofacilitate gathering a wide section of tissue between them. The distaltransverse portion 97 of jaws 92 on which teeth 96 are disposed ispreferably arcuate in shape to facilitate grasping a curved section oftissue between the jaws.

A handle 98 is attached to the proximal end of shaft 86 and includes astationary handle member 100 having finger loops 101 and a movablehandle member 102 pivotably attached to stationary handle member 100 andhaving thumb loop 103. The proximal end of rod 88 is attached to movablehandle member 102 such that pivoting the movable handle member towardthe stationary handle member pulls rod 88 proximally relative to shaft86, thereby closing jaws 92. A locking mechanism 104 facilitatesmaintaining the jaws in the closed position without maintaining pressureon handle 100.

The use of tissue gathering device 84 in the method of the invention isillustrated in FIGS. 9A–9B. Tissue gathering device 84 is introducedthrough a port 50B (FIG. 2) in the left lateral or anterior side of thechest selected to allow access to the left ventricle on the posteriorside of the heart near the apex. The heart may be retracted as necessaryto facilitate access and visualization of the left ventricle eitherdirectly or by means of a thoracoscope. Jaws 92 are positioned in theopen position against the ventricular wall VW and closed so as to gathera section of ventricular wall tissue between the jaws, as illustrated inFIG. 9A. Usually this will be an arcuate section of tissue extendingfrom a point near the apex superiorly along the left ventricle on theposterior side of the heart. Points 96 penetrate the outer surface ofthe ventricular wall to facilitate grasping the wall tissue and pursingit outwardly between the jaws. Locking mechanism 104 on handle 100 maythen be engaged so as to lock jaws 92 in position, thereby maintainingthe gathered section of ventricular wall tissue between jaws 92.

The opposing halves of the folded section of wall tissue are thenattached to one another near the base of the fold, using a large arcuateneedle 108 attached to a suture 110, driven by a thoracoscopic needledriver 112 inserted through a port 50. A running stitch may be applied,or a series of individual suture loops. Alternatively, a thoracoscopicstapler, T-fastener applier, or other suitable tissue fastening devicemay be used. The result is shown in FIG. 9B. A large section FS of leftventricle LV has been folded outwardly and isolated from the remainderof the ventricle, thereby reducing the transverse dimension and volumeof the ventricle. If desired, the outer portion of the folded section FSmay be cut off and removed using a thoracoscopic scissors or knife.Advantageously, as in the embodiment described above in reference toFIGS. 7A–7C, the left ventricle is not opened during the procedure,eliminating the risk of air embolism, and avoiding blood loss, thusallowing the procedure to be performed on a beating heart withoutcardiac arrest and CPB.

In any of the embodiments of the invention described herein it maydesirable to more accurately measure the size of the left ventricle toallow a more precise determination of the amount by which the leftventricle must be reduced. FIGS. 10 and 11 illustrate two alternativeembodiments for measuring left ventricular size. In FIG. 10, athoracoscopic heart measurement device 120 comprises a shaft 122configured for insertion through a thoracic port between the ribs, and aflexible band 124 extending from the distal end of the shaft to form aloop. Band 124 may be made of a flexible polymer or metal, and extendsslidably through an inner lumen in shaft 122 so that the size of theloop may be contracted or expanded by extending or retracting band 124from the distal end of the shaft. In this way, the loop may be placedaround the exterior of the heart H and cinched against the outer wall ofthe heart. Measurement device 120 is then removed from the chest whilemaintaining the size of the loop, which may then be measured outside thechest to determine the circumference or diameter of the heart.

An alternative embodiment of a ventricular measurement device 130 isillustrated in FIG. 11. Ventricular measurement device 130 includes ashaft 132 positionable through a right chest port 50A, through a leftatrial incision, through the mitral valve, and into the left ventricleLV. Shaft 132 therefore has a length of at least about 20 cm, andusually about 25–40 cm. An elastomeric balloon 134 is attached to thedistal end of shaft 132 and has an interior in communication with aninflation lumen extending through shaft 132. An inflation device such asa syringe 136 is attached to the proximal end of shaft 132 incommunication with the inflation lumen to facilitate delivery of aninflation fluid into balloon 134. Balloon 134 is of a size large enoughto completely occupy the left ventricle, preferably being inflatable toa diameter of 4–12 cm. In this way, measurement device 130 may beintroduced into the left ventricle via the left atrium and mitral valveand balloon 134 expanded until it engages the inner ventricular wall. Byobserving the volume of inflation fluid required to expand the balloonto this size, the approximate volume of the left ventricle may beassessed. In an alternative embodiment, a penetration may be made in thewall of the left ventricle via a port in the left lateral or anteriorside of the chest, and balloon 134 inserted directly through thepenetration to measure left ventricular volume. A purse string suturemay be placed in the heart wall around the penetration to maintainhemostasis around shaft 132.

While the above is a complete description of the preferred embodimentsof the invention, it will be understood that various substitutions,modifications, alternatives, and additions will be possible withoutdeparting from the scope of the invention, which is defined by theappended claims.

1. A method of reshaping a patient's heart comprising: inserting athorascopic measurement device into the chest of a patient, thethorascopic measurement device comprising a shaft having an inner lumenand a flexible band extending therefrom; gauging a size of a leftventricle via the thorascopic measurement device; determining an amountby which the left ventricle should be reduced from the gauging of itssize; and reducing a dimension of the left ventricle in accordance withthe determined amount.
 2. The method according to claim 1, whereingauging the size of the left ventricle comprises encircling the heartclosely with an adjustable length band, and determining the size of theventricle with reference to a length of the band.
 3. The methodaccording to claim 1, wherein gauging the size of the left ventriclecomprises inserting an expansible member into the left ventricle, andexpanding the expansible member.
 4. The method according to claim 3,wherein the expansible member is a balloon, and expanding the balloon isaccomplished by the introduction of fluid into an interior of theballoon.
 5. The method according to claim 4, wherein gauging the size ofthe left ventricle further comprises measuring the volume of fluidintroduced into the interior of the balloon.
 6. The method according toclaim 1, wherein reducing the dimension of the left ventricle comprisescreating an opening in the left ventricular wall.
 7. The methodaccording to claim 6, wherein reducing the dimension of the leftventricle further comprises removing a portion of the myocardial tissue.8. The method according to claim 6, wherein creating an opening in theleft ventricular wall comprises creating perforation in the leftventricle extending to the apex of the heart.
 9. The method according toclaim 6, wherein reducing the dimension of the left ventricle furthercomprises hemostatically closing the left ventricle.
 10. A method ofreshaping a patient's heart comprising: introducing an expansible memberthrough a chest port and into a left ventricle of the patient's heartvia a mitral valve, the expansible member being at least partiallycollapsed; expanding the expansible member within the left ventricle ofthe patient's heart; and reducing a volume of the left ventricle by anamount based upon the expanded volume of the expansible member.
 11. Themethod according to claim 10, wherein the amount of volume reduction ofthe patient's left ventricle is determined by the expanded volume of theexpansible member compared to a desired volume of the left ventricle.12. The method according to claim 10, wherein expanding the expansiblemember comprises the introduction of fluid into the interior of theexpansible member.
 13. The method according to claim 10, whereinreducing a dimension of the left ventricle comprises creating an openingin the left ventricular wall.
 14. The method according to claim 13,wherein reducing the dimension of the left ventricle further comprisesremoving a portion of the myocardial tissue.
 15. The method according toclaim 13, wherein creating an opening in the left ventricular wallcomprises creating a perforation in the left ventricle extending to anapex of the heart.
 16. The method according to claim 13, whereinreducing the dimension of the left ventricle further compriseshemostatically closing the left ventricle.
 17. A method of reshaping apatient's heart comprising: inserting a measurement device into thechest of a patient, the measurement device comprising a shaft having aninner lumen and an adjustable length band extending therefrom;encircling the heart closely with the adjustable length band;determining a size of the left ventricle with reference to a length ofthe band; and reducing a volume of the left ventricle by an amount basedupon the determined size of the left ventricle.
 18. The method accordingto claim 17, wherein reducing the volume of the left ventricle comprisescreating an opening in the left ventricular wall.
 19. The methodaccording to claim 17, wherein reducing the volume of the left ventriclefurther comprises removing a portion of the myocardial tissue.
 20. Themethod according to claim 17, wherein creating an opening in the leftventricular wall comprises creating a perforation in the left ventricleextending to an apex of the heart.
 21. The method according to claim 17,wherein reducing the volume of the left ventricle further compriseshemostatically closing the left ventricle.